Cleaning cupreous articles



Patented June 30, 1953 2,643,961 CLEANING CUPREOUS ARTICLES Clermont J. Snyder and Willis G. MacLelland,

Hastings on Hudson, N. Y., assignors to Anaconda Wire and Cable Company, a corporation of Delaware No Drawing. Application May 22, 1948, Serial No. 28,747

8 Claims. (01. 134-17.

This invention relates to removing scale from cupreous articles by heating such articles in a halogen-bearing atmosphere, and subsequently cooling them. The invention is predicated on the discovery that organic chlorinated, brominated and iodinated compounds are particularly desirable materials to employ for introducing the halogen into the atmosphere in which the article is heated.

United States Patents Nos. 2,291,201 and 2,291,202 to W. H. Bassett, Jr., C. J. Snyder and W. G. MacLelland describe processes for cleaning cupreous articles by halide treatment, thereby to remove the oxide scale that is always present on such hot-worked shapes as hot-rolled copper rods from which wire is drawn. The process of Patent No. 2,291,201 involves heating the cupreous article in a furnace atmosphere containing the vapor of a volatilizable metal halide, and thereafter cooling the article, preferably by quenching in water. The process of Patent No. 2,291,202 involves first dipping the article in an aqueous solution of a chloride, then heating the article in a furnace, and finally cooling the article as by quenching. The processes of both of these patents have been used very successfully, but that of Patent No. 2,291,201 has commercial advantages because no preliminary dipping of the article to be cleaned into a solution is necessar Vge have now discovered that substances of the class consisting of chlorinated, brominated and iodinated organic compounds may be used in place of the volatilizable metal halides described in Patent No. 2,291,201, for the purpose of establishingan effective halogen-bearing atmosphere within the furnace in which the cupreous articles are treated. Moreover, We have discovered that the use of such organic compounds for this purpose has distinct advantages that do not ensue from the use of a volatilizable metal halide. One such advantage is that when an organic compound of the class mentioned is used, the article may be heated more rapidly and its treatment may be completed sooner than with metal halide vapors. Another advantage is that batch-type treatment of a weighed amount of the articles with a weighed amount of the organic compound is possible, resulting in closer control over the quality of the cleaning treatment.

In general the present method for cleaning cupreous articles is similar to that described in Patent No. 2,291,201, and involves heating the articles to be cleaned in a halogen-bearing atmosphere to a temperature of about 1250 F'.,

and subsequently cooling them. The invention, however, provides for introducing the halogen into the atmosphere in which the cupreous article is heated by heating a chlorinated, brominated or iodinated organic compound to above its decomposition temperature, and introducing the gaseous decomposition products thereof into said atmosphere. (References herein to a halogen-bearing atmosphere are not meant to imply that the halogen is necessarily present in the atmosphere in elemental form.)

When the halogen content of the atmosphere is provided by vapor from a volatilizable metal halide, as described in Patent No. 2,291,201, most effective cleaning is accomplished by heating the article at the rate of about 50 F. per minute from room temperature up to about 700 F., so that the article is held for a totaltime of twelve to fifteen minutes at a temperature below 700 F. This appears to be due to the need for some of the halogen or halogen-bearing compound to collect on the article and react initially with its oxide scale; and such evidently occur mosteffectively with metal halide vapor at a temperature in the range from 500 F. to 700 F. We have found that when chlorinated, brominated or iodinated organic compounds are used in place of volatilizable metal halides to supply the halogen content .of the treatment atmosphere, the time of heating at a temperature below 700 F. need be only two to five minutes, and that it may be at a lower temperature, down to 300 F. Consequently about ten minutes or so may be saved in the time required for treating the article by using such an organic compound instead of a volatilizable metal halide, and furnace equipment of given size can be made to handle a correspondingly greater amount of cupreous articles per day.

We believe the reason why the use of organic compounds permits of more rapid treatment than the use of volatilizable metal halides, is that organic compounds decompose at a much lower temperature than that at which most metal halides yield substantial quantites of vapor. When the halogen is supplied as a metal halide vapor, an appreciable length of time is required for an effective amount of it to accumulate on the article; but when a chlorinated, brominated or iodinated organic compound is employed, decomposition thereof takes place so rapidly and at such a low temperature, and quickly yields so high a concentration of reactive halogen-bearing decomposition products in the furnace atmosphere,

that an effective amount of the halogen collects V on and reacts very rapidly with the article.

Fluorinated organic compounds, however, do not in general result in satisfactory cleaning of the article. It appears that the decomposition products of fluorinated organic compounds are themselves too stable to react effectively with the copper of the article. Accordingly the invention is limited to the use of chlorinated, brominated and iodinated organic compounds, all of which are indicated to be highly effective, rather than being broadly directed to the use of all halogenated organic compounds.

Another advantage found to result from the use of chlorinated, brominated and iodinated organic compounds in lieu of volatilizable metal halides is that batch-type cleaning operations can be employed, using a measured (usually weighed) amount of the organic material to treat a weighed quantity of cupreous articles. When a volati1iz-' able metal halide is employed, it is not feasible to measure the amount of metal halide vapor that is used to treat any given quantity of articles. Consequently, closer control over the cleaning operation is possible when using one of these organic compounds than when a volatilizable metal halide is employed.

There appears to be nothing critical about the type of organic compound employed in accordance with the invention, except that it must be chlorinated, brominated or iodinated. It is generally preferred to use a chlorinated organic compound, because such compounds are readily available, relatively inexpensive, and very effective. Organic compounds of both bromine and iodine, though less available and more costly, are also very effective and may be used. The type of organic molecule in which the chlorine, bromine or iodine is included, or the way in which it is bound in the molecule, appears to be of no consequence. Tests with a very large number of such organic compounds have been uniformly successful in achieving good results, and have indicated that all chlorinated, brominated and iodinated organic compounds can be used. For practical reasons, however, it is easiest commercially to employ compounds that are normally solid.

Following are examples of ways in which the method of the present invention may be carried out:

Example 1.A weighed quantity of hot-rolled copper rods, having a scale composed mainly of cuprous and cupric oxides, and at room temperature, is introduced into an electrically heated muffle-type furnace. Along with the rods, a crucible containing a weighed quantity of a normally solid chlorinated, brominated or iodinated organic compound is introduced into the furnace, and the furnace is then closed. (Instead. of introducing the organic compound in a crucible, it may be just sprinkled or scattered on the rods.) The material in the furnace is heated rapidly until the rods have reached a temperature of about 1250 F., the furnace itself being heated to about 1300 F. With cupreous articles as massive as hot-rolled copper rod for wire-drawing (which usually are about three-eighths of an inch in diameter), the rods may be brought to their final temperature about as rapidly as the furnace can heat them. When they have been heated about to 1250 F., the furnace is opened, and the rods are withdrawn and cooled to room temperature. Cooling may be in any manner desired as pointed out in Patent No. 2,291,201), but generally it is convenient and most satisfactory to quench the rods in water. When the rods have cooled, a

' held in the oven for two to five minutes, but it is not necessary that they be heated to the oven temperature-it is only necessary that they be exposed to the heated oven atmosphere for the length of time stated. They are then transferred from the oven to a furnace in which they may be heated rapidly to a final temperature of about 1250 F. (The furnace may be entirely separate from the oven, or oven and furnace may be but two parts of the same heating apparatus.) The furnace atmosphere may be free of any halogen or halogen-bearing compound during this latter period of heating, a the preliminary oven treatment has resulted in an effective accumulation of chlorine, bromine or iodine in reactive form on the rod surfaces. After attaining a tempera ture of about 1250 R, the rods are withdrawn from the furnace and cooled, as by quenching. In the method of this example, the rods may be introduced directly into the furnace from the oven, or they may be held for some time in the air and allowed to cool to room temperature between the oven treatment and the furnace treatment, whichever is the more convenient.

Each of the preceding examples is based on batch-type operation, in which a weighed quantity of rods is treated with a weighed quantity of the organic compound. As previously stated, this procedure has the advantage of giving close control over the extent to which the rods are attacked, and the amount of scale formed and removed. It is not necessary, however, that the method of the invention be carried out batchwise. It is possible instead to employ a continuous type furnace such as i described in Patent No. 2,291,201, and merely substitute an organic chlorinated, brominated or iodinated compound for the metal halide. Such a substitution results in making the process more rapid, as previously mentioned herein. If a continuous-type furnace is employed, and if a temperature gradient is maintained in the furnace, as described in Patent No. 2,291,201, it is generally preferable to introduce thehalogenated organic compound into the cold end of the furnace, rather than into the hot end as is done with the metal halide. Organic compounds in general decompose at a low enough temperature so that it is not necessary for them to be heated to the maximum tempera ture of the furnace; and the decomposition products from the organic compound collect more efficiently on the rods or other articles, and enable the preliminary reaction that appears to take place at a temperature below 700 F. to proceed more readily, when the organic compound is introduced at a point near where the cold rods enter.

Furthermore, if a fuel-fired furnace is used, as described in Patent No. 2,291,201, it is best to design it so that fuel combustion gases do not enter the region where the rods or other articles are being treated. We have found that fuel combustion gases interfere somewhat with the effectiveness of the treatment when a chlorinated, brominated or iodinated organic compound is used as the source of the halogen for the treatment atmosphere. However, the presence of oxygen (or air) in the treatment atmosphere has been found to be advantageous. The readily separable scale that is formed by the halide treatment seems to be an oxyhalide, and its formation evidently is favored by the presence of some oxygen in addition to that already present in the initial tightly-adhering scale of cuprous and cupric oxides.

As previously stated tests have indicated that all chlorinated, brominated and iodinated organic compounds can be used effectively in the method of the invention. We have tried many different organic compounds of this class and have found none that do not give at least fairly satisfactory results. The following table lists a number of the compounds that have been employed, and also indicates whether the results obtained were excellent, good, or fair (in all cases the results were commercially satisfactory). In addition, the table shows the per cent of the original weight of the hot-rolled copper rods (which were the articles treated) that was lost in the scale.

Table I Wt. Less in Quality of Organic Compound Scale 1% Cleaning Saturated Aliphatic Compounds:

Carbon tetrachloride 1 2. '4 Fair.

Iodoform 1 3. Excellent.

Ethylene dichloride 2. 0 Good.

Acetyl bromide 1 2. 2 Do.

Ethyl iodide l. 9 Excellent.

Methyl amine hydrochlo de 1 2. 1 Do.

Chlorinated paraflin 1 2. 4 Good. Unsaturated Aliphatic Compounds Vinyl chloride l. 5 Do.

Allyl chloride. 1 2. 5 Do.

Allyl bromide 1. 1 Excellent. Polymers:

Polyvinylchloride l. 5 Good.

Polymerized chloroprene 2.0 Do.

Copolymerized vinyl acetate and l. 5 Do.

vinyl chloride.

Chlorinated rubber l. 5 Do. Benzene Ring Compounds:

Dichlorbenzene 2. 0 Do.

Aniline hydrochloride- 2.1 Do.

Chlorinated diphenyl 1. 0 Do. Miscellaneous Ring Compound Creatinine zinc chloride 1.0 Fair.

Naphthylamine hydrochloride l. 5 Good.

Oamphor monobromide 1 2. 3 Excellent.

1 Scale losses in excess of 2% are greater than necessary for good cleaning and sometimes leads to pitting of the article. Such heavy scaling is due to using more of the organic compound than is required, An excess of the compound, however, does not make the cleaning less eficctiveit simply results in removing more metal from the article than is desirable in the best practice. Some of the results reported in this table are based on tests made before learning the optimum amount of the particular organic compound to employ.

The amount of organic compound required is ordinarily quite small (but of course depends to some extent on the proportion of halogen to nonhalogen elements which make up its molecule). With most organic compounds, we have found that an amount ranging from two to five pounds of organic compound per ton of hot-rolled copper rods is adequate to give excellent results. Indeed, as pointed out in the footnote to the table above, too large a quantity of the organic compound should be avoided in order to prevent an excessive loss of metal in the scale. Optimum results are obtained in the case of hot-rolled copper rods for Wire-drawing, when the amount of scale removed is from 1% to 2% of the weight of the rods, and advantageously about 1.5%. Larger or smaller amounts of the organic compound, and a larger or smaller percentage of metal lost in the scale, will, however, be preferable when the article being treated has an appreciably different ratio of surface to volume than ordinary hot-rolled copper rods for wire-draw- An incidental advantage of the use of chlorinated organic compounds in treating copper rods for the wire industry is that scrap chlorinated plastic material commonly available in wire mills can be used as the source of thehalogen. For example, such materials as neoprene (polymerized chloroprene), Koroseal and Geon (both being polymerized vinyl chloride) and Vinylite (a copolymer of vinyl chloride and vinyl acetate) are quite commonly used for wire insulat ion and scrap quantities of these materials can be used with excellent results.

We claim:

1. In a process for removing scale from a cupreous article involving heating the article in a halogen-bearing atmosphere and subsequently cooling the article, whereby the scale separates readily therefrom, the improvement which comprises introducing the halogen into the atmosphere in which the cupreous article is heated by heating a, substance of th class consisting of chlorinated, brominated and iodinated organic compounds to above its decomposition temperature and introducing the gaseous decomposition products thereof into said atmosphere.

In a process for removing scale from a cupreous article involving heating the article in a chlorine-bearing atmosphere and subsequently cooling the article, whereby the scale separates readily therefrom, the improvement which comprises introducing the chlorine into the atmosphere in which the cupreous article is heated by heating a chlorinated organic compound to above its decomposition temperature and introducing the gaseous decomposition products thereof into said atmosphere.

3. In a process for removing scale from a cupreous article involving heating the article in a halogen-bearing atmosphere and subsequently cooling the article, whereby the scale separates readily therefrom, the improvement which comprises introducing the article into a furnace, also introducing into the furnace a substance of the class consisting of chlorinated, brominated and iodinated organic compounds, producing gaseous decomposition products of said organic compound by heating \it in the furnace to above its decomposition temperature while heating the cupreous article therein rapidly to about 1250 F., and then removing the article from the furnace and cooling it.

4. In a process for removing scale from a cupreous article involving heating the article in a chlorine-bearing atmosphere and, subsequently cooling the article, whereby the scale separates readily therefrom, the improvement which comprises introducing the article into a furnace, also introducing into the furnace a chlorinated organic compound, producing gaseous decomposition products of said organic compound by heating it in the furnace to above its decomposition temperature while heating the cupreous article therein rapidly to about 1250 F., and then removirgg the article from the furnace and coolmg 1 5. In a process for removing scale from cupreous articles involving heating the articles in a halogen-bearing atmosphere and subsequently cooling the articles, whereby the scale separates readily therefrom, the improvement which comprises introducing a weighed batch of said articles into a, furnace, introducing a corresponding measured quantity of a normally solid substance of the class consisting of chlorinated, brominated and iodinated organic compounds into the furnace, producing gaseous decomposition products 7 r of said organic compound by heating it in the furnace to above its decomposition temperature while heating the cupreous articles therein rapidly to at least a temperature in the range from 300 F. to 700 F., thereafter further heating the cupreous articles to about 1250 F., and then removing the articles from the furnace and cooling them. A

6. In a process for removing scale from cupreous articles involving heating the articles in a chlorine-bearing atmosphere and subsequently cooling the articles, whereby the scale separates readily therefrom, the improvement which comprises introducing a weighed batch of said articles into a furnace, introducing a corresponding measured quantity of a normally solid chlorinated organic compound into the furnace, producing gaseous decomposition products of said organic compound by heating it in the furnace to above its decomposition temperature while heating the cupreous articles therein rapidly to at least a temperature in the range from 300 F. to 700 F., thereafter further heating the cupreous articles to about 1250 F., and then removing the articles from the furnace and cooling them.

'7. In a process for removing scale from a cupreous article involving heating the article in a. halogen-bearing atmosphere and subsequently cooling the article, whereby the scale separates readily therefrom, the improvement which comprises heating a substance of the class consisting of chlorinated, brominated and iodinated organic compounds to above its decomposition temperao 8 ture, introducing the gaseous decomposition products thereof into an oven, heating the cuprcous article in said oven at a temperature in the range from 300 F. to 700 F. for a few minutes, then transferring the cupreous article to a furnace and heating it rapidly therein to about 1250 F., and thereafter removing the article from the furnace and cooling it.

8. In a process for removing scale from a cupreous article involving heating the article in a chlorine-bearing atmosphere and subsequently cooling the article, whereby the scale separates readily therefrom, the improvement which comprises heating a chlorinated organic compound to above its decomposition temperature, introducing the gaseous decomposition products thereof into an oven, heating the cupreous article in said oven at a temperature in the range from 300 F. to 700 F. for a few minutes, then transferring the cupreous article to a furnace and heating it rapidly therein to about 1250" F., and thereafter removing the article from the furnace and cooling it.

CLERMONT J. SNYDER. WILLIS G. MACLELLAND.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,371,644 Petering Mar. 20, 1945 2,371,645 Aitchison Mar. 20, 1945 

1. IN A PROCESS FOR REMOVING SCALE FROM A CUPREOUS ARTICLE INVOLVING HEATING THE ARTICLE IN A HALOGEN-BEARING ATMOSPHERE AND SUBSEQUENTLY COOLING THE ARTICLE, WHEREBY THE SCALE SEPARATES READILY THEREFROM, THE IMPROVEMENT WHICH COMPRISES INTRODUCING THE HALOGEN INTO THE ATMOSPHERE IN WHICH THE CUPREOUS ARTICLE IS HEATED BY HEATING A SUBSTANCE OF THE CLASS CONSISTING OF CHLORINATED, BROMINATED AND IODINATED ORGANIC COMPOUNDS TO ABOVE ITS DECOMPOSITION TEMPERATURE AND INTRODUCING THE GASEOUS DECOMPOSITION PRODUCTS THEREOF INTO SAID ATMOSPHERE. 